Html form + anchor postback trouble

Having the following sample:

<form id="form" name="form" method="post">
    <a id="submit1" name="submit1" href="javascript:doPostBack('submit1', '')">#1</a>
    <a id="submit2" name="submit2" href="javascript:doPostBack('submit2', '')">#2</a>
    <a id="sub开发者_StackOverflow社区mit3" name="submit3" href="javascript:doPostBack('submit3', '')">#3</a>
</form>

What is the doPostBack function code should be, so that on the server I could distinguish which anchor was pressed?

You can use a hidden input element to track the source of submit and at the server end check the source of submit. e.g:

<form id="form" name="form" method="post">
    <input type="hidden" value="" name="submitSource"/>
    <a id="submit1" name="submit1" onclick="registerSubmitSource(this)" href="javascript:doPostBack('submit1', '')">#1</a>
    <a id="submit2" name="submit2" href="javascript:doPostBack('submit2', '')">#2</a>
    <a id="submit3" name="submit3" href="javascript:doPostBack('submit3', '')">#3</a>
</form>
<script type="text/javascript">
 function registerSubmitSource(el)
 {
  var submitSource = document.getElementById("submitSource");
  submitSource = el.tagName; 
  return;
 }
</script>